Fuse plug



May 20, 1947.

T. R. OCONNOR 2 ,837

FUSE PLUG Filed Jan. 21, 1944 2 Sheets-Sheet 1 Inventor Thomas A? 0 Zb/mw" By @Wm (ma yaw 5M May 20, 1947. OCONNOR 2,420,837

FUSE PLUG Filed Jan. 21, 1944 1 2 Sheets-Sheet 2 5 n v 5 I Inventor Patented May 20, 1947 UNITED STATES PATENT OFFICE FUSE PLUG Thomas R. OConnor, Baltimore, Md. Application January 21, 1944, Serial No. 519,179

2 Claims.

This invention relates to certain new and useful improvements in what is believed to be a novel type fuse plug and has more particular reference to a renewable fuse element and coacting parts which facilitate its replacement and serve to maintain it in place in the plug proper.

As implied in the preceding opening statement of the invention, I am sufficiently conversant with the prior art to realize that the broad idea of constructing a plug with a renewable fuse element is notoriously old. I am aware that prior patentees long since discovered the need for a removable and replaceable fuse element, this to conserve on materials by thus allowing the plug proper to be used over and over. I aim to accomplish the same results but do so through the instrumentality of a structurally novel and refined selection and arrangement of details.

In carrying out the principles representing the preferred embodiment of my invention I have succeeded in devising and perfecting a simple and economical construction in which the elements, collectively considered, appropriately fulfill the chief requirements of the trade.

Other features and advantages will become more readily apparent from the following description and the accompanying illustrative drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the views:

Figure 1 is a top plan view of a fuse plug constructed in accordance with the principles of the present invention.

Figure 2 is a side elevation taken at right angles to Figure 1, that is, a view observing Figure 1 in a direction, let us say, from right to left.

Figure 3 is a top plan view with the removable adapter element omitted to expose the details appearing therebeneath.

Figure 4 is a central vertical section on the plane of the line 44 of Figure 1.

Figure 5 is a bottom plan view.

Figure 6 is a perspective view of the removable and replaceable fusible element.

Referring now tothe drawings by distinguishing reference numerals it will be noted that the customary or conventional insulated plug proper is denoted by the numeral 1. This includes the usual cylindrical body portion 8 and corrugated annulus or ring 9 for threading the plug into the fuse box socket (not shown). As brought out in Figure 4 the body is provided with diametrically opposite bores or passages 10 to accommodate spring metal contact fingers H and 12. The

lower end of the finger II is electrically connected with the pressed metal cap l3 held in place by the usual headed button or pin M. The corresponding lateral end of the finger I2 is in electrical contact with the adjacent portion of the shell or ring '9. It will be observed that the upper ends of the fingers are flared outwardly as at l5 to serve as detents. The head portion 16 is provided, as brought out in Figure 3, with a relatively shallow groove I! which serves as a receiving and keeper seat for the adapter insert is. The insert 18 is of glass and fits removably and snugly into the keeper seat IT. The central portion is formed with a, depression I9 which constitutes a clear glass window for inspection of the U-shaped fusible element 20. The latter part as seen in Figure 6 includes short parallel limbs 2| which telescope into the bores I0. These limbs hug the inner walls of said bores and occupy positions in the crotches formed by the flaring detents Hi. The central or bight portion 22 is narrowed as usual to melt and break when an overload of current passes therethrough. It will be noticed that the insert or adapter I8 is provided with spaced L-shaped metal prongs 23 whose projecting end portions also protrude or telescope intothe bores in. These prongs frictionally engage the limbs 21 of the fusible element and also have electrical contact with the flaring ends [5 of the contact fingers II and I2. Thus current is transferred from the ends IE tothe prongs and from the prongs to the limbs 2 I.

In case the fusible element 20 is blown the break is clearly visible through the clear glass window l9, which of course, signifies the need for a substitute or replacement fuse. In such circumstances the adapter insert is simply detached from the plug body in an obvious manner and the fuse 20, that is, the burnt fuse is removed and a new one is put in its place. Then, the parts are replaced to occupy the positions shown in Figure 4.

If desired, the bottom of the insert may be provided with projecting lugs to engage in notches formed in the body, whereby to facilitate frictional retention of the insert.

It is thought that persons skilled in the art to which the invention relates will be able to obtain a clear understanding of the invention after considering the description in connection with the drawings. Therefore, a more lengthy description is regarded as unnecessary.

Minor changes in the shape, size and. arrangement of details coming within the field of invenwhat is claimed said contact arms and between which diverging,

portion and said body, said arms and limbs are wedged, and means whereby elementsclose an electric circuit.

2. In a device as described a fuse body including an enlarged annular head provided with a transverse centrally disposed slot extending thereacross, a glass insert removably seated in said 4 slot, a fusible element held within said body by the insert, said fusible element having depending limbs, said insert having depending contact arms, adapted to secure the said element in place, and a pair of conductor arms diverging adjacent to said contact arms and between which diverging portion and said body, said arms and limbs are wedged.

THOMAS R. OCONNOR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,488,420 Watts Mar. 25, 1924 1,545,781 Long July 14, 1925 2,144,134 Wood Jan, 17, 1939 20 2,170,168 Vanderveer Aug. 22, 1939 

